Referring to FIG. 1, FIG. 1 illustrates a top view of typical reflective spatial light modulator mirror devices. A mirror device 102 of a typical reflective spatial light modulator is formed above a substrate 100, and a mirror layer 104 of the mirror device 102 is supported by a hinge layer 106 and is separated from the substrate 100 with a distance, wherein the hinge layer 106 is supported by supporting posts 108. Furthermore, on the hinge layer 106, a contact opening 110 is formed, and the contact opening 10 is filled with the hinge layer 106 made of a conductive material, so that the hinge layer 106 is directly connected to the mirror layer 104. Because the material of the mirror layer 104 is a conductive material, the hinge layer 106 is electrically connected to the mirror layer 104.
Referring to FIG. 2 to FIG. 6, FIG. 2 to FIG. 6 are schematic flow diagrams showing the conventional process for manufacturing reflective spatial light modulator mirror devices, wherein the cross-sectional views of FIG. 2 to FIG. 6 are obtained along cross-sectional line I—I shown in FIG. 1. A sacrificial layer 114 is first formed by using a deposition method to cover a substrate 100 which is transparent, and a mirror layer 104 is formed by using a sputtering method to cover the sacrificial layer 114, wherein the material of the sacrificial layer 114 is dielectric material and the material of the mirror layer 104 is metal. Then, a photolithography technique and an etching technique are used to define the mirror layer 104, thereby removing a portion of the mirror layer 104 to form openings 116 on the sacrificial layer 114 and expose a portion of the sacrificial layer 114, and meanwhile, a mirror pattern of the mirror device 102 is transferred onto the mirror layer 104, such as shown in FIG. 2.
After the mirror pattern of the mirror device 102 is transferred onto the mirror layer 104, a sacrificial layer 118 is formed by using a deposition method to cover the mirror layer 104 and the sacrificial layer 114 exposed by the openings 116. Then, a definition step is performed by using a photolithography technique and an etching technique, and a portion of the sacrificial layer 118 is removed to expose a portion of the mirror layer 104, so as to form a contact opening 110 of the mirror layer 104 in the sacrificial layer 118 on the portion of the mirror layer 104, such as shown in FIG. 3.
After the contact opening 110 of the mirror layer 104 is formed, a definition step is performed by using a photolithography method and an etching method similarly, and a portion of the sacrificial layer 118 located in the openings 116 is removed to expose a portion of the substrate 100, so as to form contact openings 120 of the substrate 100 in the opening 116, such as shown in FIG. 4. Besides, the contact openings 120 of the substrate 100 can be formed before the contact opening 110 of the mirror layer 104 is formed.
After the contact opening 110 of the mirror layer 104, and the contact openings 120 of the substrate 100 are formed, a support material layer (of which only a support layer 122 and the supporting posts 108 are shown) is formed by using a deposition method to cover the sacrificial layer 118; the mirror layer 104 exposed by the contact opening 110; and the substrate 100 and the sacrificial layer 114 exposed by the contact openings 120. Then, a portion of the support material layer is removed by using an etching back method until the surface of the sacrificial layer 118 is exposed. At this point, the remaining support material layer within the contact openings 120 forms the supporting posts 108, and the remaining support material layer within the contact opening 110 forms the support layer 122. The contact opening 110 is wider, so that after etching back step is performed, the bottom of the contact opening 110 is not entirely covered by the support layer 122 within the contact opening 110, and a portion of the mirror layer 104 is exposed, such as shown in FIG. 5.
Then, a material film of the hinge layer 106 is formed by using a sputtering method to cover the sacrificial layer 118, the supporting posts 108, the support layer 122, and the mirror layer 104 exposed by the contact opening 110, wherein the material of the material film of the hinge layer 106 is a conductive material. A patterning definition step of the hinge layer 106 is performed by using a photolithography method and an etching method, so as to form the hinge layer 106 on a portion of the sacrificial layer 118; the support layer 122; the supporting posts 108; the contact openings 120; the mirror layer 104 exposed by the contact opening 110; and the contact opening 110, such as shown in FIG. 6. The supporting posts 108 in the contact openings 120 can be used to support the hinge layer 106, and the hinge layer 106 in the contact opening 110 is directly connected to the mirror layer 104. After the sacrificial layer 114 and the sacrificial layer 118 are removed, the hinge layer 106 is first supported by the supporting posts 108, and the mirror layer 104 is hanged via the direct connection of the hinge layer 106 and a portion of the mirror layer 104.
However, referring to FIG. 3 and FIG. 4., because a portion of the sacrificial layer 114 is stacked with the sacrificial layer 118, and the adhesion between the sacrificial layer 114 and the sacrificial layer 118 is poor, the sacrificial layer 114 and the sacrificial layer 118 peel off easily, and thus the process reliability is reduced. Next, referring to FIG. 3 and FIG. 4 again, during the aforementioned process for manufacturing the reflective spatial light modulator mirror devices, the sacrificial layer 118 and the sacrificial layer 114 need to be etched while the contact openings 120 of the substrate 100 are manufactured, and only the sacrificial layer 118 needs to be removed while the contact opening 110 of the mirror layer 104 is manufactured. Hence, the contact openings 120 of the substrate 100 and the contact opening 110 of the mirror layer 104 need to be manufactured respectively, and thus process steps are increased. Moreover, while the etching back step of the support material layer is performed, a portion of the support material layer in the contact openings 120 is removed, so that the structural strength of the supporting posts 108 formed in the contact openings 120 is reduced.